We are building an A-team of highly skilled and autonomous engineers, and we are seeking an exceptional PySpark Big Data Senior Developer to join our dynamic and focused squads. This role is for a hands‑on player/coach who thrives in a high‑autonomy environment, is deeply committed to leveraging AI for maximum productivity, and possesses a profound understanding of the functional domains our work impacts. The ideal candidate will be instrumental in designing, developing, and optimizing large‑scale data processing solutions using PySpark and cutting‑edge big data technologies. We are looking for an AI‑first thinker who can raise the bar, coach others, and strategically contribute to our evolving technology landscape. Responsibilities Operate end‑to‑end in the design, development, and implementation of robust big data solutions, ensuring optimal performance, scalability, data quality, and security. Collaborate closely within small, co‑located squads (4‑7 person teams), fostering high communication and low coordination overhead, to translate complex business requirements into technical specifications for big data processing and analytical solutions. Act as a player/coach within the team, mentoring junior members and leading by example in the development of efficient and innovative big data architectures. Design, develop, and optimize large‑scale data pipelines using PySpark for data ingestion, transformation, and aggregation, always with an eye toward efficiency and domain relevance. Implement and manage real‑time data streaming and event‑driven architectures using technologies like Apache Kafka. Design and implement sophisticated data warehousing solutions and dimensional models for efficient data storage and retrieval, ensuring alignment with business needs. Work with various distributed data storage technologies, including distributed file systems (e.g., HDFS, S3) and NoSQL databases (e.g., MongoDB, Cassandra), selecting the right tool for the right problem. Implement efficient data processing and storage strategies to optimize the performance and scalability of big data applications, with a strong focus on the "why" behind the technology choices. Champion best practices in software development, including rigorous code reviews, implementing comprehensive testing, and supporting continuous integration and continuous deployment (CI/CD) pipelines. Demonstrate high autonomy and agency in driving projects forward, making informed decisions, and proactively identifying areas for improvement. Proactively leverage and contribute to the development of AI‑powered development tools, including internal Citi AI tools like Copilot, Claude Code, Codex, and Antigravity, to significantly enhance productivity, code quality, and accelerate development cycles. Lead technical discussions and contribute strategically to the evolution of our big data technology stack, always seeking innovative approaches. Troubleshoot and resolve complex technical issues within big data environments, demonstrating strong analytical and problem‑solving skills. Required Skills & Experience Experience: 6+ years of extensive, hands‑on experience as a Senior Big Data Developer, with a strong emphasis on PySpark and the Apache Spark ecosystem, operating as a player/coach. Programming Languages: Expert proficiency in Python, with a proven track record of developing robust, scalable, and high‑performance PySpark applications for large‑scale data processing. Big Data Frameworks/Technologies: Deep understanding and extensive hands‑on experience with Apache Spark (Spark Core, Spark SQL, Spark Streaming) and its ecosystem. Experience with distributed computing frameworks such as Hadoop (HDFS, YARN). Data Storage & Warehousing: Expert proficiency in SQL and extensive experience with data warehousing concepts and technologies (e.g., Hive, Snowflake, Redshift, Databricks SQL). Proven experience with various data storage formats (e.g., Parquet, ORC, Avro) and data lake solutions (e.g., Delta Lake, Iceberg). Experience with NoSQL databases (e.g., MongoDB, Cassandra, HBase) is a significant plus. Messaging & Event Streaming: Strong experience with Apache Kafka for building real‑time data pipelines and event‑driven architectures. Cloud Platforms: Demonstrated experience with big data services on major cloud platforms (e.g., AWS EMR/Glue/Redshift, Azure Databricks/Data Factory/Synapse, GCP Dataflow/Dataproc/BigQuery) is highly desirable. AI‑Powered Development & Productivity: Proven effectiveness with AI coding tools (e.g., Claude Code, Codex, Antigravity) is a mandatory requirement. A strong "AI‑first thinker" mindset, demonstrating how to leverage and integrate AI tools into the development workflow for continuous improvement. Experience with or a strong willingness to actively explore and implement other AI‑powered tools to optimize big data development processes. Domain Understanding: Strong ability to articulate the functional domain being worked in, understanding the business context, and explaining "why" the technical solutions matter. Other Essential Skills: Advanced understanding of data structures, algorithms, and performance optimization techniques for large‑scale distributed data processing. Experience with RESTful API design and development for data ingestion or exposure points. Familiarity with containerization technologies (e.g., Docker, Kubernetes) for deploying and managing big data applications. Expert proficiency with version control systems, especially Git, and advanced branching strategies. Exceptional problem‑solving, analytical, and debugging skills in highly complex, distributed big data environments. Superior communication and interpersonal skills, with a proven ability to work effectively and autonomously within small, high‑performing teams, and to mentor others. Demonstrated high autonomy and agency in tackling complex challenges and delivering impactful solutions. Education Bachelor's or Master's degree in Computer Science, Engineering, Data Science, or a related quantitative field is required. Equivalent practical experience with a demonstrable track record of excellence will also be considered. EEO Statement Citi is an equal opportunity employer, and qualified candidates will receive consideration without regard to their race, color, religion, sex, sexual orientation, gender identity, national origin, disability, status as a protected veteran, or any other characteristic protected by law. If you are a person with a disability and need a reasonable accommodation to use our search tools and/or apply for a career opportunity review Accessibility at Citi. View Citi’s EEO Policy Statement and the Know Your Rights poster. #J-18808-Ljbffr